Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1998-06-29
2000-04-11
Denion, Thomas
Power plants
Internal combustion engine with treatment or handling of...
Methods
60276, 60285, 60286, 123443, F01N 300
Patent
active
060475420
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method and a device for purifying an exhaust gas of an engine.
BACKGROUND ART
If an air-fuel ratio of an air-fuel mixture in a combustion chamber of an internal combustion engine is referred as an engine air-fuel ratio, and if a ratio of the total amount of air fed into the intake passage, the combustion chamber, and the exhaust passage upstream of a certain position in the exhaust passage to the total amount of fuel fed into the intake passage, the combustion chamber, and the exhaust passage upstream of the above-mentioned position is referred to as an exhaust gas air-fuel ratio of the exhaust gas flowing through the certain position, the Japanese Unexamined Patent Publication No. 4-365920 discloses an exhaust gas purifying device for an internal combustion engine with multi-cylinders, the engine having first and second cylinder groups, in which the device is provided with: an engine operation control device to make each cylinder of the first cylinder group a rich engine operation in which the engine air-fuel ratio is rich, and to make each cylinder of the second cylinder group a lean engine operation in which the engine air-fuel ratio is lean; a first exhaust passage connected to each cylinder of the first cylinder group; a second exhaust passage connected to each cylinder of the second cylinder group and different from the first exhaust passage; an NH.sub.3 synthesizing catalyst arranged in the first exhaust passage for synthesizing ammonia NH.sub.3 from at least a part of NO.sub.x in the inflowing exhaust gas; an interconnecting passage interconnecting the first exhaust passage downstream of the NH.sub.3 synthesizing catalyst and the second exhaust passage to each other; and an exhaust gas purifying catalyst arranged in the interconnecting passage to reduce NO.sub.x from the second exhaust passage by NH.sub.3 from the first exhaust passage.
In the above engine, the fuel consumption rate is reduced by increasing the numbers of the cylinders of the second cylinder group in which the lean engine operation is performed. However, if the numbers of the cylinders of the first group are decreased and the numbers of the cylinders of the second group are increased, the NH.sub.3 amount flowing into the exhaust gas purifying catalyst decreases and the NO.sub.x amount flowing into the catalyst increases. As a result, the NO.sub.x amount flowing into the catalyst may be excessive with respect to the NH.sub.3 amount, and thus NO.sub.x may be emitted from the catalyst without being reduced sufficiently.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a method and a device for purifying an exhaust gas of an engine which can suppress the amount of NO.sub.x flowing into an exhaust gas purifying catalyst with respect to that of NH.sub.3, to thereby purify the exhaust gas sufficiently.
According to one aspect of the present invention, there is provided a method for purifying an exhaust gas of an engine having a plurality of cylinders divided into first and second cylinder groups, the method comprising: making an exhaust gas air-fuel ratio of the exhaust gas of the first cylinder group rich, and introducing the exhaust gas to an NH.sub.3 synthesizing catalyst to synthesize NH.sub.3, the NH.sub.3 synthesizing catalyst synthesizing NH.sub.3 from at least a part of NO.sub.x in the inflowing exhaust gas when the exhaust gas air-fuel ratio of the inflowing exhaust gas is rich; introducing the exhaust gas of the first cylinder group including NH.sub.3 and the exhaust gas of the second cylinder group including NO.sub.x together to an exhaust gas purifying catalyst; and controlling an amount of NO.sub.x included in the exhaust gas of the second cylinder group and to be introduced to the exhaust gas purifying catalyst to prevent the NO.sub.x amount from being larger than a NO.sub.x amount which can be reduced by the NH.sub.3 included in the exhaust gas of the first cylinder group and to be introduced to the exhaust gas purifying catalyst, wherein,
REFERENCES:
patent: 3767764 (1973-10-01), Dolbear
patent: 3810361 (1974-05-01), Weaving et al.
patent: 3825654 (1974-07-01), Kobylinski et al.
patent: 3953576 (1976-04-01), Meguerian et al.
patent: 4321792 (1982-03-01), Achard
patent: 4393031 (1983-07-01), Henke
patent: 4395875 (1983-08-01), Virk
patent: 4854123 (1989-08-01), Inoue
patent: 5021227 (1991-06-01), Kobayashi et al.
patent: 5207058 (1993-05-01), Sasaki et al.
patent: 5313792 (1994-05-01), Katoh et al.
patent: 5367875 (1994-11-01), Aboujaoude et al.
patent: 5384098 (1995-01-01), Morikawa
patent: 5406790 (1995-04-01), Hirota et al.
patent: 5410873 (1995-05-01), Tashiro
patent: 5412946 (1995-05-01), Oshima et al.
patent: 5461857 (1995-10-01), Itou et al.
patent: 5473887 (1995-12-01), Takeshima et al.
patent: 5479775 (1996-01-01), Kraemer et al.
patent: 5540047 (1996-07-01), Dahlheim et al.
patent: 5551231 (1996-09-01), Tanaka et al.
patent: 5595060 (1997-01-01), Togai et al.
patent: 5605042 (1997-02-01), Stutzenberger
patent: 5609026 (1997-03-01), Berriman et al.
patent: 5628186 (1997-05-01), Schmelz
patent: 5657625 (1997-08-01), Koga et al.
patent: 5661971 (1997-09-01), Waschatz et al.
patent: 5740669 (1998-04-01), Kinugasa et al.
patent: 5746052 (1998-05-01), Kinugasa et al.
patent: 5758493 (1998-06-01), Asik et al.
patent: 5778667 (1998-07-01), Kinugasa et al.
patent: 5782087 (1998-07-01), Kinugasa et al.
patent: 5783160 (1998-07-01), Kinugasa et al.
patent: 5791139 (1998-08-01), Atago et al.
patent: 5826425 (1998-10-01), Rossi Sebastiano et al.
Igarashi Kouhei
Itou Takaaki
Kinugasa Yukio
Suzuki Naoto
Takeuchi Kouichi
Denion Thomas
Toyota Jidosha & Kabushiki Kaisha
Tran Binh
LandOfFree
Method and device for purifying exhaust gas of engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for purifying exhaust gas of engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for purifying exhaust gas of engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1168395